Photographic layers suitable for the silver dyestuff bleaching process



United States Patent 3,210,190 PHOTOGRAPHIC LAYERS SUITABLE FOR THE SILVER DYESTUFF BLEACHING PROCESS Walter Anderau, Aesch, Basel-Land, and Rudolf Mory,

Dornach, Solothurn, Switzerland, assignors to Ciba Limited, Basel, Switzerland, 21 company of Switzerland No Drawing. Filed Jan. 24, 1962, Ser. No. 168,511 Claims priority, application Switzerland, Jan. 26, 1961,

910/61 8 Claims. (CI. 96-99) In the substractive photographic process for the production of color transparencies and color pictures to be viewed by reflected light, a yellow component image is required, the yellow dyestulf of which absorbs light in the visible spectrum up to about 500 mm, but allows light of higher wave-lengths to be completely transmitted. Visually, such a dyestuff is pure lemon yellow. When this yellow component image is produced by the silver dyestutf bleaching process, there are required appropriate azo-dyestuffs that are capable of being bleached. Pure yellow azo dyestuffs which conform to the optical requirements can be found among those which contain the radicals of acetoacetylaminobenzenes or of pyrazolones. These dye stuffs, however, generally have the disadvantage that they are either not bleached at all or are only partially bleached in the usual silver dyestufi bleaching process.

The present invention provides photographic layers suitable for the silver dyestuff bleaching process, whic contain at least one dyestulf of the formula:

in which R represents the radical of a diazo-component having a benzene nucleus bound to the azo group, and R represents the radical of a S-imino-pyrazoline which is bound in the 4-position to the azo group and in the 1-position to a naphthalene or benzene nucleus, and in which all the azo groups present in the molecule are bound on one side to a benzene nucleus and on the other to the radical of a S-imino-pyrazoline. The dyestuffs to be used for the present process are of pure yellow shade and are easy to bleach out in the silver dyestuff bleaching process.

The simplest examples of such dyestuffs are monoazodyestuffs which are obtained by coupling a diazotized amine of the benzene series with an imino-pyrazole. If the dyes contain water-solubi-lizing groups, such as carboxylic acid or sulfonic acid groups, they should nevertheless be fast to diffusion, for the purposes of the silver dyestulf bleaching process, or have as low a capacity for diffusion as possible. This may be achieved by increasing the size of the dyestuff molecule, for example, by using a diazo-component whose molecule is enlarged by carboxy or sulfoxy groups. It is generally advantageous for the dyestuffs of the Formula 1 to contain in the radical R an acyl group, for example, of the type of the benzoylamino group. Furthermore, the acyl groups may be those, for example, of higher fatty acids, such as lauric acid or palmitic acid. Furthermore, the diaZo-components may, for example, correspond to the formula:

in which A represents an aliphatic or aromatic radical, and Y represents a water-solubilizing group. A diazocomponent of this kind is, for example, the compound of the formula:

Especially suitable for the production of water-soluble dyestuffs having little or no capacity for diffusion, are diazo-components that impart substantive properties, that is to say, those which yield dyestuffs having an afiinity for cellulose fibers. As examples of such diazo-components there may be mentioned:

HOaS

and

HaC

HOaS

in which R, represents a naphthalene radical or preferably a benzene radical which may contain further substituents, for example, those mentioned above in connection with the diazo-components, but especially water-solubilizing groups, such as sulfonic acid groups.

Instead of monoazo-dyestuifs, the photographic layers may contain disazo-dyestuifs of the above general constitution. Such disazo-dyestulfs may, for example, correspond' to the formula:

in which R represents the radical of a diazo-component containing a benzene nucleus bound to the azo group, R represents a benzene radical, and X represents a direct bond or a bridge member.

These disazo-dyestuifs are obtained by coupling a coupling component of the formula:

in which R and X have the meanings given above, on both sides with a diazo-component of the benzene series,

A further group of valuable diazo-dyestuffs corresponds to the formula:

SOaH

HgN O I O NH;

| SOaH HOaS R:H or CH and it is also advantageous in this case to use diazo-components which are obtained from components of the type referred to; above in connection with the monoazodyestuifs.

The benzene radicals R may contain further substitucuts, and the bridge member --X- may be, for example, one of the following atomic groupings:

Z:a halogen atom or a hydroxyl group of an organic radical or an amino group.

ll 0 S0311 ll 0 0 H N H-C NH;

The monoazoand disazo-dyestufls may be prepared by methods in themselves known by coupling the diazotized monoamines or diamines in a weakly acid to weakly alkaline medium with the irnino-pyrazolines capable of coupling once or twice.

When the dyestuifs contain no Water-solubilizing groups, they are pigments which cannot be brought into aqueous solution and cannot be fixed to substr-ata like water-soluble dyestuffs, and must therefore be finely and uniformly dispersed in the photographic layers. It is necessary for this purpose to reduce them to a particle size not exceeding 0.5;], by means of a suitable apparatus. The dyestuffs which contain acid water-solubilizing groups are generally obtained as the alkali metal salts thereof, and are advantageously used in that form for dyeing the photographic layers.

These dyestulfs exhibit a strong absorption in the wave-length range of 400480 mg, a sharp fall in absorp ti-on above 480 m and a high degree of transparency at :and abov 500 mg.

The yellow dyestuffs of the constitution defined above may be used as filter dyestufis, but especially in the construction of a multi-layer material for the production of color pictures to be viewed by reflected light or color transparencies. The water-soluble yellow dyestulfs which are capable of diffusing, can be used, for example, for coloring gelatine image layers or tanned gelatine images which are used in transfer processes or imbibition processes for building up a multi-color picture.

An important advantage of these dyestuffs is their capacity for being bleached in the silver dyestufi bleaching process. The yellow dyestuffs are especially suitable for incorporation in a multi-layer material which con- 5 6 tains on a transparent or white pigmented support three Gelatines colored with these dyestuifs are prepared in lightsensitive silver halide .gelatine layers, which are known manner by dissolving the dyestuif in hot water, colored green-blue, blue-red and yellow, and are sensicooling the dy-estuff solution to about 40 C., and then tized according to their natural color relationship. mixing the solution with an aqueous gelatine solution of The following examples illustrate the invention, the 5 10% strength at about 40 C. and stirring the mixture. parts and percentages being by weight unless otherwise The dissolution of the dyestuff may be facilitated by addstated, and the relationship of parts by weight to parts by ing an alcohol, such as methanol, ethanol or glycol mono- Volume being the same as that of the kilogram to the methyl ether.

liter. By dissolving, for example, 0.041 gram of dyestuff of Example 1 10 Formula 19 in 2.5 cc. of water, mixing the solution with There is used one of the following dyestuffs, which 2.5 cc. of a gelatine solution of 10% strength, and castcan be Prepared in the usual manner: ing the whole on a glass plate having an area of 1 square decimeter and then drying the layer, there is obtained a (15) yellow layer having an optical density of 2.5 at a wave- Hoss R E 15 length of 436 m '500 gnarns of a yellow colored gela- C-N tine so obtained are mixed with 1000 grams of a silver C O I halide emulsion containing 35 grams of silver. After casting the emulsion on the desired carrier, it is exposed, HO 5 and then treated in the following manner:

H30 20 (1) Developed for 5 minutes in one of the usual metolor 3 hydroquinone-sodium carbonate developers (1000 cc. (16) EN CH3 3 w C-N- SOaH II I] 0 O 0:

(18) EN O-CHa (l1:

I H2Ns02 (.1:

NH HOS HN k i l- -Q I N=C C=N SOa (l3 CH3 H3 I R HOS R l k t 2* N Q l Oti O e l :0 O O:

SOaH CH3 HaC R=H 01 CH3 7 of water containing 1 gram of N-rnethyl-para-aminophenol, 13 grams of anhydrous sodium sulfite, 3 grams of hydroquinone, 26 grams of anhydrous sodium carbonate and 1 gram of potassium bromide);

(2) Washed in water for 2-3 minutes;

(3) Fixed for minutes in a bath containing 1000 cc. of water, 200 grams of sodium thiosulfate and 20 grams of potassium metabisulfite;

(4) Washed in water for 5 minutes;

(5) Hardened in a formaldehyde solution of 4% strength for 5 minutes;

(6) Washed in water for 5 minutes;

(7) Bleached for minutes in a bath containing in 1000 parts of water, 30-90 parts of potassium bromide, 20 '50 parts of thiourea, 30-75 parts of concentrated hydrochloric acid and 1-2 parts of a solution of aminohydroxyphenazine of 0.1% strength;

(8) Washed in water for 3 minutes;

(9) Rinsed for 3 minutes in sodium carbonate solution of 10% strength;

(10) Washed in Water for 3 minutes;

(11) Bleached for 5 minutes as in 7;

(12) Washed in water for 5 minutes;

(13) The silver is bleached for 3 minutes in a bath conof the mill are then washed out with 30 parts of water, and homogeneously mixed with 150 parts of a gelatine solution of 8% strength. 100 parts of this colored gelatine are mixed with 50 parts of silver bromide emulsion, and the mixture is cast on glass plates. The emulsion layer is then exposed behind a stepped wedge, and the silver image is developed in a metol-hydroquinone de veloper, and then fixed. After hardening in dilute formaldehyde solution, the dyestutf layer is locally bleached to an extent depending on the quantity of silver locally present, in a bath containing per 1000 parts by volume, 30-75 parts by volume of hydrochloric acid of 37% strength, 309O parts of potassium bromide, 2050 parts of thiourea and 0.0010.01 part of amino-hydroxyphenazine. The excess of silver is then bleached in a bath containing, per 1000 parts by volume, 100 parts of sodium chloride, 100 of crystalline copper sulfate and 50 parts by volume of hydrochloric acid of 37% strength, and then fixed in the usual manner. A yellow dyestuif wedge is obtained which is the reverse of the original silver Wedge.

The azo-pigments of the following formulae may be used instead of the azo-pigment of the Formula 23:

taining in 1000 parts of water, 100 parts of crystalline copper sulfate, 20 parts of hydrochloric acid and 80 parts of sodium chloride;

(14) Washed in water for 3 minutes;

(15) Fixed in the bath used in 3 for 5 minutes;

(16) Washed in water for 10 minutes;

(17) Dried.

A yellow component image is obtained, which may form part of a multi-layer material, for example, as a yellow layer together with a purple layer and a cyan layer of the usual compositions.

Example 2 0.5 part of the dyestulf pigment of the formula I C=N or (obtainable by coupling diazotized Z-methoxy-S-chlorol-amino-benzene with 1-(4'-methylphenyl)-3-methyl-5- irnin-opyrazoline) is ground with 0.5 part of a sodium alkylnaphthalene sulfonate and 20 parts of water in a ball mill which is free from metal parts, for example, in an Attritor mill (Labor model), until practically all the dyestuif has a particle size smaller than 0.5 r. The contents What is claimed is:

1. A photographic layer for the silver dyestuft bleaching process, which contains silver halide and at least one monoazo dyestufl corresponding to the formula in which R represents the radical of a diazo component having a benzene nucleus bound to the azo group, and R represents the radical of a S-imino-pyrazoline which is bound in the 4-position to the azo group and in the 1-position to an aromatic nucleus selected from the group consisting of a naphthalene nucleus and a benzene nucleus, and in which all the azo groups present in the molecule are bound on one side to a benzene nucleus and on the other to the residue of a S-imino-pyrazoline.

9 10 2. A photographic layer for the silver dyestuff bleach- 8. A photographic layer for the silver dyestuff bleaching process, which contains silver halide and at least one ing process, which contains silver halide and the dyestuif dyestuff of the formula of the formula r R -N-C /(ENR4 5 fiCN=N-R5N =NC H N= C=N HN l l (|]OH3 y)N- CH H O a in which R represents a benzene radical and R repre- N:N CH l sents the radical of a tetrazo compound bound to both I O=N azo groups directly by the carbon atom of a benzene ring. 1

3. A photographic layer for the silver dyestuff bleaching process, which contains silver halide and at least one dyestuff of the formula in which R and R represent benzene radicals and m 5 and n each represents a whole number of at the most 2.

4. A photographic layer for the silver dyestufi bleaching process, which contains silver halide and the dyestutf of the formula 5. A photographic layer for the silver dyestutf bleaching process, which contains silver halide and the dyestulf of the formula 6. A photographic layer for the silver dyestuff bleaching process, which contains silver halide and the dyestuif of the formula F I Q N=C i') o C=N I HOaS l CH3 H30 7. A photographic layer for the silver dyestufl bleach- References Cited by the Examiner ing process, which contains silver halide and at least one UNITED STATES PATENTS dyestutf of the formula 3,114,634 12/63 Brown et al 9620 fi FOREIGN PATENTS 952,019 11/56 Germany. OTHER REFERENCES C=N Cornwell-Clyne: Colour Cinematography, page 420, 11 Chapman and Hall, 37 Essex Street, London, 1951.

in which R; and R each represent a monocyclic benzene NORMAN TORCHIN Primary Examinerradical free from water-solubilizing groups. LOUISE P. QUAST, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,210,190

Walter Anderau et a1.

October 5,

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 10, formula in claim 8 should appear as shown below instead of as in the patent:

Signed and sealed this 5th day of July 1966.

(SEAL) Attest:

ERNEST W., SWIDER EDWARD J6 BRENNER Attesting Officer Commissioner of Patents 

1. A PHOTOGRAPHIC LAYER FOR THE SILVER DYESTUFF BLEACHING PROCESS, WHICH CONTAINS SILVER HALIDE AND AT LEAST ONE MONOZAO DYESTUFF CORRESPONDING TO THE FORMULA 